The 29-year-old goalkeeper has joined the U’s on a two-year deal, after being released by Championship-bound Portsmouth at the end of last season.
Colchester have been on the lookout for a new goalkeeper for next season, following Owen Goodman’s return to parent club Crystal Palace after his loan spell and Sam Hornby’s release.
Macey started his career at Bristol Rovers but did not make a first-team appearance for them.
The 6ft 6in keeper joined Premier League club Arsenal in 2013 and played for the Gunners in both the EFL Cup and Europa League.
Macey featured for Arsenal in a 2-1 win over Norwich City in the Carabao Cup in the 2017/18 season and also in their 0-0 draw with Red Star Belgrade, in the Europa League.
He was on the bench for every game in the Premier League and FA Cup for the final weeks of the 2019/20 season following an injury to Bernd Leno and collected an FA Cup winners medal after Arsenal beat Chelsea, at Wembley Stadium.
During his time at the Emirates Stadium, Macey had loan spells at Accrington Stanley, Luton Town and Plymouth Argyle before he left Arsenal in 2021 to join Scottish Premiership side Hibernian.
He spent a year at the Edinburgh club before returning south of the border to rejoin Luton on a permanent basis, in the summer of 2022.
Macey joined Portsmouth on loan in January 2023, a few days after Danny and Nicky Cowley had departed the club.
He eventually signed for the South Coast club on a permanent basis 12 months later and played regularly for them in the 2022-23 season but did not make an appearance, in the latest campaign.
Colchester are on the hunt for more new signings, as they attempt to bolster their squad ahead of the 2024-25 season.